<HTML><HEAD><TITLE>overlay(+MapA, +MapB, -Map)</TITLE>
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<H1>overlay(+MapA, +MapB, -Map)</H1>
Overlays one map over another.
<DL>
<DT><EM>MapA</EM></DT>
<DD>A map
</DD>
<DT><EM>MapB</EM></DT>
<DD>The map to overlay
</DD>
<DT><EM>Map</EM></DT>
<DD>The resulting map
</DD>
</DL>
<H2>Description</H2>
	<P>
	The map Map contains a key/value pair for every key that appears in
	either the map MapA or the map MapB.  If a key Key appears in MapB,
	then its corresponding value in Map is that appearing in MapB;
	otherwise it is that appearing in MapA.
	</P>
	<P>
	This predicate should only be called with maps created by other
	predicates from the map module.
	</P>
	
<H3>Fail Conditions</H3>
Never fails.
<H3>Resatisfiable</H3>
no
<H2>See Also</H2>
<A HREF="../../lib_public/m_map/merge-3.html">merge / 3</A>
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